Space data highway experiment delivers first images

Two European satellites have exchanged data across a 45,000km distance using a laser communications terminal designed to form the basis of a future space data highway.

Images of Earth were sent from the European Space Agency's (Esa) Sentinel-1A satellite, orbiting about 700km above the Earth, via Inmarsat’s geostationary satellite Alphasat, which is about 36,000km away from the Earth's surface.

The experiment demonstrated the viability of the planned €450m (£358m) space data highway that will link low-Earth orbiting satellites with ground-based control centres via powerful laser links delivered through geostationary satellites, which hang above a fixed spot on Earth.

"Currently, a satellite downloads the data that it acquires whenever it is within view of one of four ground stations on Earth," said Josef Aschbacher, head of Esa’s Earth Observation Programme Planning & Coordination Service.

"That means there can be periods of 45 to 90 minutes from the visibility of one station to another.”

The use of geostationary satellites will remove the need to wait, allowing the controllers to view the images nearly instantaneously – a major advantage in situations requiring immediate intervention such as natural disasters and military operations.

Moreover, the space data highway, also called the European Data Relay System (EDRS), will allow increasing bandwidth enabling transmission of large amounts of data.

While the experimental transmission last week achieved only 0.6 Gigabits per second, the target capacity is expected to reach up to 1.8 Gigabits per second, equivalent to transmitting all the data that could be printed in a 1m-long shelf of books.

“This is a major step in the proof of the concept,” said Evert Dudok, head of the Communications, Intelligence and Security (CIS) Business Line at Airbus Defence and Space, the company that designed and built the laser communication terminals for both satellites.

Eventually, the project partners believe, the capacity of the space data highway could be increased to up to 7.2 Gigabits per second

The first post-test operational terminal of the space data highway constellation has been already mounted on Eutelsat’s 9B spacecraft to be launched next year to be followed with a second dedicated satellite a year later. Together the two satellites and Imarsat’s Alphasat, which carried out the test, will provide complete coverage of the globe.

Apart from environmental observations in the framework of Europe’s Copernicus programme, the system will also allow beyond-line-of-sight monitoring and command of Unmanned Aerial Systems, constant maritime border surveillance and an easier way to control and re-configure satellites in orbit.

The demonstration, following a 2008 test between two low-Earth orbit satellites, will pave the way for Airbus to receive the final green light from the European Commission to go ahead with the project.

Airbus Defence and Space will be commissioned to operate the system on behalf of the European Space Agency, with the final contract expected to be signed by the end of this year.